Automated functional image-guided radiation treatment planning for rectal cancer

Journal Article · Fri Jul 01 04:00:00 EDT 2005 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2004.12.089· OSTI ID:20698594

Ciernik, Ilja Frank ^[1]; Huser, Marius ^[2]; Burger, Cyrill ^[3]; Davis, J Bernard ^[1]; Szekely, Gabor ^[2]

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1. Department of Radiation Oncology, Zurich University Hospital, Zurich (Switzerland)
2. Computer Vision Laboratory, Swiss Federal Institute of Technology, Zurich University Hospital, Zurich (Switzerland)
3. Department of Nuclear Medicine, Zurich University Hospital, Zurich (Switzerland)

Purpose: Computer tomography-based (CT-based) tumor-volume definition is time consuming and is subject to clinical interpretation. CT is not accessible for standardized algorithms for the purpose of treatment-volume planning. We have evaluated the accuracy of target-volume definition based on the positron emission tomography (PET) data from an integrated PET/CT system with 2-[{sup 18}F]fluoro-2-deoxy-D-glucose (FDG) for standardized target-volume delineation. Materials and Methods: Eleven patients with rectal cancer who were undergoing preoperative radiation therapy (RT) were studied. A standardized region-growing algorithm was tested to replace the CT-derived gross tumor volume by the PET-derived gross tumor volume (PET-GTV) or the biologic target volume (BTV). A software tool was developed to automatically delineate the appropriate tumor volume as defined by the FDG signal, the PET-GTV, and the planning target volume (PTV). The PET-derived volumes were compared with the target volumes from CT. Results: The BTV defined for appropriate GTV assessment was set at a single peak threshold of 40% of the signal of interest. Immediate treatment volume definition based on the choice of a single-tumor volume-derived PET-voxel resulted in a tumor volume that strongly correlated with the CT-derived GTV (r {sup 2} = 0.84; p < 0.01) and the volume as assessed on subsequent anatomic-pathologic analysis (r {sup 2} = 0.77; p < 0.01). In providing sufficient extension margins from the CT-derived GTV and the PET-derived GTV, to PTV, respectively, the correlation of the CT-derived and PET-derived PTV was sufficiently accurate for PTV definition for external-beam therapy (r {sup 2} = 0.96; p < 0.01). Conclusion: Automated segmentation of the PET signal from rectal cancer may allow immediate and sufficiently accurate definition of a preliminary working PTV for preoperative RT. If required, correction for anatomic precision and geometric resolution may be applied in a second step. Computed PET-based target-volume definition could be useful for the definition of standardized simultaneous internal-boost volumes for intensity-modulated radiation therapy (IMRT) based on biologic target volumes.

• OSTI ID: 20698594
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 3 Vol. 62; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ACCURACY
ALGORITHMS
COMPUTER CODES
FLUORINE 18
GLUCOSE
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NEOPLASMS
PATIENTS
PLANNING
POSITRON COMPUTED TOMOGRAPHY
RADIOTHERAPY
SPATIAL RESOLUTION